Edit a Canvas App

Make the following changes to the existing Canvas App:

$ARGUMENTS

Overview

Two paths depending on edit complexity:

• Simple edits (≤2 controls, ≤1 screen, no new screens/data) — handled inline
• Complex edits (multiple screens, new screens, structural changes) — via planner + editor agents

Plugin root: the directory containing skills/, agents/, and references/

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Phase 0 — Create App Folder

1. Derive a short folder name from $ARGUMENTS — extract the app name or use a 2–3 word summary
2. Convert to kebab-case
3. Create the folder: mkdir -p <folder-name>
4. Resolve its absolute path — this is the working directory

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Phase 1 — Sync and Check

Call sync_canvas targeting the working directory. This pulls the current app state from the coauthoring session into local .pa.yaml files.

After sync, read the files and check if the app has meaningful content. An app is empty if:

• No .pa.yaml files were written, or
• No screens with actual controls (non-container children) exist

If empty, inform the user and switch to the full generate-canvas-app workflow.

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Phase 2 — Assess Complexity

Simple — ALL of these are true:

• Changes affect ≤2 controls or properties
• Changes are confined to ≤1 screen
• No new screens, data sources, or structural layout changes

Complex — ANY of these are true:

• Changes span multiple screens
• New screens need to be created
• New data sources or connectors are required
• Structural layout changes involved

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Phase 3a — Simple: Direct Edit

Read ../../references/TechnicalGuide.md.

Apply changes directly to the relevant .pa.yaml files.

Call compile_canvas on the working directory. Iterate until clean.

Present summary:

Edit complete. [1-2 sentence description.] Compiled clean after [N] pass(es).

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Phase 3b — Complex: Plan (Edit Planner Agent)

Read the edit planner agent definition:

• ../../references/TechnicalGuide.md
• ../../references/DesignGuide.md
• ../../agents/canvas-edit-planner.md

Adopt the role of canvas-edit-planner and follow every step in that file with:

• Edit requirements: $ARGUMENTS
• Working directory: the absolute path from Phase 0
• Plugin root: the directory containing skills/, agents/, and references/
• List of synced .pa.yaml files

Do not proceed to Phase 4 until the user approves the plan.

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Phase 4 — Edit (Complex path only, Screen Editor Agent)

After the planner completes, read canvas-edit-plan.md from the working directory.

Extract screens to modify and screens to add.

For each affected screen, in sequence:

1. Read the editor agent definition: ../../agents/canvas-screen-editor.md
2. Adopt the role of canvas-screen-editor for this screen
3. Follow every step in that file with:
   • Screen name and action (Modify / Add)
   • Target file name
   • Plan document path
   • Working directory

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Phase 5 — Validate and Fix (Complex path only)

Call compile_canvas on the working directory. Iterate until clean.

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Phase 6 — Summary

Delete canvas-edit-plan.md:

rm <working-directory>/canvas-edit-plan.md

Present final summary table of all screens modified/added, compilation passes, any remaining errors.